Construction of automatic pressure alarm



Jan. 8 1924.

' F. M. EVELEIGH CONSTRUCTION oF AUTOMATIC PRESSURE ALARM Filed July 11 FIG'. 2

FTE'.

Patented Jan. 8, 1924.

UNITED STATESl FRANK' MONTAGUE EVELEIGH, or AUcKLANnNEW ZEALAND. i

CONSTRUCTION OF ATOMATIC PRESSUREALARM.

Application iledJuly 11, 1922. Serial No. 574,161.

To all who/m, 'it may concern.'

Be it known that I, FRANK MONTAGUE EVELEIGH, subject of the King of Great Britain, residing at Epsom, Auckland, New Zealand, have invented anew and useful Improved Construction of Automatic Pressure Alarm, of which the following is a specification.

My invention relates to an improved construction of automatic alarm for use in in dicating a reduction of pressure in air and the like pressure systems and more .particularly designed for use in the air brake apparatus of tramway and other vehicles in order to give an audible alarm when the pressure is reduced below certain predetermined degree'.

VThe said alarm device is designed to be positioned at any convenient point in the air pressure system and is so constructed that while the usual working pressure is maintained, certain parts of the device will be retained in positions such as to close air ports adjacent to a whistle device, and when the pressure is reduced, will automatically act to open such ports and permit of the escape of pressure through them. This air then being directed on to the whistle, will cause the whistle to sound and thereby give the alarm. f

The appliance is illustrated in the accompanying drawings and will be herein after fully explained in relation to such drawings, in which- Figure l is an elevation of the appliance.

Figure 2 is a sectional elevation thereof.

Figure 3 is a sectional plan taken on the line 3 3 of Figure 2.

Figure 4 is a sectional plan taken on the line 4-4 of Figure 2.

The alarm is formed by a cylindrical cas ing A closed at its inner end by a cap A having means for its connection with the air system as the coupling a and also having a plate B with apertures therein, eX- tending across its end between the casing and the said cap. The outer end of the casing A is closed by a screw plug C fitting into it and formed with a central bore C eX- tending right through and the outer end of which is enlarged as at C2 and female screw threaded to receive the threaded socket piece end of a pin D, the other end of which has the whistle E attached to ist. The plug C is also formed with a number of port passages F radiating from the bore C within the position of the socket piece-y of the pin D and then `bending outwards through the end of the plugaroundthe.

said whistle pin. These passages Fl may enter atftheir4v outer ends into fa groove op j in the end of the plug and such' groovemay s have positioned in it a spreader lflange D formed on the said pin which will serve to spread the air jets ythat emerge through the passages F, into a ring and thendirect such on to the whistle.

Fitted into the cylindrical casing A is a piston G and attached to lit or formed integral therewith is a hollow sleeve H that makes a neat sliding fit within the bore C of the plug C'. The pistony G itself is formed witha central recess J in,

a. line continuous with the bore of the sleeve H and the opening of such recess is formed its outer end. .This stem K is made of a cross sectional shape such as to leave` spaces between its surface andy the inner wall of: right through vits. length, as for instance, the triangular shape the bore extending shown in Figures 3 and. A spring M surrounds the stem K within ythe recess J in the piston, and serves. normally `to press the valve K in from its seat over such recess.` The piston itself is spring controlled by a spring contained withinthe casing A |between the pistonrandtheouter end `.of y thev said casing and this spring serves to force the piston inward on to the plate B and when in such position the sleeve H uncovers the ports F in the plug bore beforementioned. This spring, however, is so adjusted that in the normal conditions of affairs, under which the full air pressure of the system is acting on the inner side of the piston, the piston will be forced outward in the casing A and the sleeve H will project across and cover the said ports` F, as shown by the full lines in Figure 2. The valve K too by reason of this pressure upon it will be kep-t on its seat and its stem K in engagement with a buffer washer O on the inner face of the socket piece D at the outer end of the plug bore.

When the pressure falls below the fixed degree, the spring M controlling the valve K will force the same away from its seat When the normal pressure isl restored the over the;recessed,y thereby allowingl the compresse'dainoff' the system to 4pass up the-bore:` of the sleeve H. The spring N controlling the piston G willalsoacttoforce the ,piston in so that the sleeve H' will be likewise' moved in to uncover-the ports-1E inqthe plug,y

as indicated by the dottedlines in Figure 2,

and thereby allow the air, pressure tofpass .up

through the sleeve, escape through the ports F, andE being directed oni te e thek whistle E mounted? on. the-I end? of' the` device thus to sound' the whistle iny the mannerl desire-d.'

radialibores opening` from the side i ofV the' centralfbore andithen extending out through tlebsa-idplug; a whistle devicemounted? at the outerii end ofy thecent'ral bore andi on'to.

which the .saidfportsf open', a piston I movably. mounted in# the` said cylinderl and? beingi underithefpressureiof the'isystem, a spring,-

controllingsaid piston and" adaptedt to move it? inwardsfwhenithe said pressure falls'y below-fa predetermined amount, and a hollow sleevejattachedffto the. outerv sideV of said'. pis'- ton opening; through: the piston, and: tting theifb'ore in 'thev` said-l4 plug, adaptedf to I close the said? port openings: when .the said.' piston moves" outward and to uncover.'- them` when tleipistonf moves inwards;

2. pressure al'arf'm comprising a cylinf` derfa'd'apted tobe conn'ectedan its inner endy with the'wfp-ressure system,` aplugclosingits-A outer end and?! having ports' extending.;

through it-gtoithe router side, af whistle 'device mounted? upony suchzpl'u'gzy and; on to which the fsaid?E p'ortsi open,-

springf'controlled `mov` able pfistonhaving a central opening? fitted inf/9,797

within the saidcylinder soias to'moveoutwards fwiththe normal'pressure ofthe pressure system in the inner end of the cylinder, andv inwardswhen such pressure decreases, means'upon the said'pi'ston whereby the said portsmay tie-*closed andfopened by the respective movements of the piston in and out, a'. spring controlledfvalve fitted over the iiislde of the opening through the piston and adapted while the normal pressurel off-the system is maintained tor-seal such opening, and when thev pressure decreases to uncover 1t. A t

3. A pressure alarm comprisingaI cylinderl adapted to be-connected atitsrinnerendf' with the' pressure system, Y a plug -closingf its v outer end and having a centrally extendingy bore and ports opening radially, from the bore andextendingzoutf through the endof the said: plug, a whistle device mounted at? the outer endof: the bfore, ar niovable-piston having a central opening through it, 'a hollowv sleeve extending,` from its outer side ro'mf such opening and; fitting" within the bore l, of, the said plug f so. as to slide therein with the movements of the said` piston, aj

valve fittedy in the inner sidef ofV thek said piston for closing the openingy through it; and having. its stem; loosely fitting within` the said: sleeve,- a spring controllinggf such l valve so `as toppermitf the same to closewlifen the normal pressure fromv the systemv is maintained` in, thel ,inner endf of the cylinderY andf to force it open when such, pressure is,l

reduced, and a springi controlling the said piston so, asto provide for it moving outwardswith the maintenance' ofthe systems pressure and inwards when such' pressuredecreases.

In testimonywhereoff, I afiix: my signature.

FTRANKI MONTAGUE rvr-Leren;

Witnesses DAVID yBnowini Hn'rfroN, ROBERTVEDWARD B ATTY; 

